Pharmacokinetics

Question 1

How do drugs get transported around the body? In terms of speed of onset of drug effects, which route of administration do you think is the fastest?

Answer 1

drugs get around the body via the bloodstream
the faster a drug gets into the bloodstream (eg, intravenous injection), the faster it will get around the body  the fastest way to get it into the bloodstream is to inject it

Question 2

What protects the brain from bad things in the blood (like bacteria)? Explain.

Answer 2

the blood brain barrier
cell membranes are made of fat, so a drug cannot reach body tissues if it is not fat soluble, since body tissues are made of cells

Question 3

Describe how the liver detoxifies drugs.

Answer 3

the liver contains enzymes that turn drugs into polar (water soluble) compounds
the liver also contains enzymes that add glucuronic acid to drug molecules, to make them more water-soluble

Question 4

If a drug has a half-life of 2 hours, how long does it take for that drug to be (practically speaking) eliminated?

Answer 4

12 hours, because it takes 6 half-lives to metabolize a drug down to very low levels

Question 5

What is the difference between tolerance and dependence? To answer this question, do not just cut and paste the definitions. Think about how the 2 are different and put that difference into your own words.

Answer 5

tolerance means that the effects of a drug lessen with repeated exposure, whereas dependence means that a drug must be taken, or withdrawal symptoms will be felt
tolerance can happen in the absence of dependence